Method and apparatus for making photographic prints



Jan. 31, 1939.

H. J. BRUNK METHOD AND APPARATUS FOR MAKING PHOTOGRAPHIC PRINTS Filed March 14, 1935 3 Sheets-Sheet 1 jaw/war Mwss: a/cgltcifi/ywvfi WK, Mu 1W6.

Jan. 31, 1939.

s Sheets- Sheet 2 Filed March 14, 1935 wwmss H. J. BRUNK Jan. 31, 1939.

METHOD AND APPARATUS FOR MAKING PHOTOGRAPHIC PRINTS 3 Sheets-Sheet 3 Filed March 14, 1935 I I II 55:

Patented Jan. 31, 1939 UNITED STATES PATENT, OFFICE Harold J. Brunk, Chicago, 111., assignor to The C. F. Pease Company, a corporation of Delaware Application March 14, 1935, Serial No. 11,142 I 15 Claims.

My invention relates to improvements in methods for making blue prints. In developing such prints water is used, resultingin so-called bleeding, 1. e. discoloration of the white areas by the blue coloring material. My invention is directed more particularly to the substantial elimination of this bleeding or running of the color.

As pointed out in Patent 1,861,298 which issued May 31, 1932, based on my application filed May 11, 1931, the sensitized coating of the usual blue print is applied as a solution containing mixtures of potassium ferricyanide and organic salts of iron such as ferricammonium oxalate. During the period of exposure to such light the potassium ferricyanide is partly reduced to potassium ferrocyanide while the ferric ammonium oxalate is reduced to ferrous ammonium oxalate.

After exposure, the paper is washed with clear water which removes all the unexposed soluble chemical from the areas which were behind the opaque. portion of the tracing or negative and also removes the loose exposed or reduced chemical, i. e. that portion which does not adhere to the fibre's of the paper. This washing, in a cer- 25 tain sense, also starts the process of oxidation of the reduced chemical-which action is necessary in the formation of the blue lines or areas. In other words, if left long enough in the water the so-called potash treatment hereinafter re- 30 ferred to, is unnecessary. It is the practice, however, to complete the oxidation by applying bichromate of potash or some oth'erstrong oxidizing agent'to the surface of the paper immedi ately after the'application of. the first water 35 wash. Theexcess bichromate or potash must be washed OK the surface by applying a second water wash, after which the paper isreadyior drying; 1 a a T Prints made in this manner are far from sat- 40 isfactory or dependable when first class. blue-' "prints with clear white lines --or blue line prints on a clear iwhitebackground are desired. The diflicult ten ed l th fully. exposed chemical in certain "area r mg n h'daw iiP Z aa i 45 white .orgn xpq ed areas as, soon i 1 3 offlow' oversthe su i Q Q5. h P e aus thus" staining .the'white area t m water to the print, and is successful even when theblue printing machine is operated at a comparatively high rate of speed. One method of my present invention obviates the use of a special developer, requiring merely the application 5 of water, except, of course, for the subsequent application of the usual fixing bath or potash which completes the oxidation. The new process has the advantage, therefore, that it follows the general sequence heretofore employed for years 10 in making blue prints, except for an additional preliminary water treatment of a special character, and, furthermore, the equipment used may be very similar to standard continuous blue print machines except for a few attachments and incideiital alterations.

The object of the invention is to provide a new and simple method of overcoming the difliculties due torunning and bleeding heretofore inherent in the use of liquid in developing photo-copies or prints.

A contributory object is to provide a method for applying liquid to the side of the sheet opposite the one having the light sensitive coating thereon whereby the required reaction is made possible by the fact that the said liquid works its way through the sheet from the back to the front.

Another object is to provide a method for applying water to the uncoated'surface of a sheet of blue print paper to cause absorption of said water by said sheet and start the oxidation of the chemicals comprising the'coating.

In the accompanying drawings I have illustrated several embodiments of the mechanical features of the invention in the form of attachments to well known types of so-called continuous blueprinting machines, capable of carrying out the 'method. The invention may be embodied in other forms, however. 1

Fig.1 is a side elevation o f partof a blue printing machine; I

"Fig. 215 ;a side elevation of a modified Iorm oithe inventiomf I I is= aslde elevation of a further zmodiflca 45 tion" a a a side elevatio of a" -urther mcidiiica:a

negatives held against said sensitized surface whereby the printing is accomplished. The span of paper thereafter continues its travel toward the, rear of the machine, passing up and down over various rollers. The first application of water is made by passing said span of paper under one of said rollers which is being continuously sprayed .with water, this roller making contact with the back or unsensitized side of the paper, whereby the moisture thus applied soaks through the paper reaching the chemical on the coated side and causing an initial oxidation. The

paper then continues its travel, passing through the usual water wash which washes on the superfluous chemicals but without causing bleeding or running, after which the paper, as it continues its travel, is treated to an application of potash or other oxidizing agent, following which it passes through the drier and is then ready to be cut up into prints of the desired size.

Referring now to Fig. 1, the machine shown therein comprises a suitable frame l0, having a supply of blue print paper in the form of a roll mounted on a rod ll near the front ofthe machine. The paper is drawn from the roll in the form of a. span I2 which passes rearwardly over a horizontal portion or table and thence upwardly past a curved sheet of glass l3, past a row of arc lamps I4, or other suitable source of light. Said paper then passes over rollers IE, it and down under tension roller H, the shaft ll! of the latter being mounted in suitable, vertically adjustable bearings, not shown, which, however, are supported on a chain 89 whereby the paperis maintained under the proper tension. From the tension roller the paper passes over the roller 20, down under the roller 2!, over the roller 22 and under the moistening roller 23 and also past roller 25. .The last three rollers as a group cause the paper to travel in a V shaped span, whereby the moisture may be applied to the rear side thereof,

-i. e. the coated side faces downwardly. Prior to reaching this group of rollers, no water-is applied to either side of the paper. The water at this point is supplied through a pipe 25 from which it is sprayed onto the roller 23 with the result that puddles are formed on the paper, one on each side of the roller, the water which collects in said puddles running off from both ends without contacting with the sensitized surface or under surface of the paper, and is discharged in any suitable manner. Throughout this figure of the drawings the reference 62, indicating the span of paper, is applied to the sensitized side from which'it will be seen that the arrangement of therollers 2!, 22, 23 and :24 is for the further purpose of turning the paper upside down with reference to its position as it enters the machine initially and in general as it travels rearwardly.

The application of moisture to the back of the paper at this point in its travel is the important feature of the invention as the water is permitted to soak through the paper for a long enough period for oxidation to take place before the paper enters the conventional water wash at the top of the unit, as hereinafter described.

Heretofore, water has not been applied to the back of paper as it passes through a blue print machine except for preventing curling of the paper stockafter the print has passed the usual water wash where the water is applied to the front or coated surface of the print. My im- .proved method differs from the prior practice in applying moisture to the back of the print in advance of the application of water to the coated side of said'print and in applying it in such a way that it may soak through the paper and reach the chemical from the rear.

With the particular arrangement described herein, the water which runs off from the edges of the paper is caught by a suitable V shaped pan 26, surrounded by another tank 21, provided with a suitable outlet. In order to adjust the operation of the machine for the different speeds at which the paper may travel and to afford the necessary time for the moisture to soak through the paper before it reaches the usual water wash at the top of the unit, the supporting frame 28 for the three rollers 22, 23 and 24 may be adjusted vertically on suitable supports 29.

' The water wash at the top of the unit is indicated generally by 30 and comprises rolls 3|, 32 and 33, around which the paper passes and at which point it is washed by water delivered in a spray from pipe 34 against the roller 32. An additional back wash 35 may be applied to the sheet as it descends over the roller 36, to prevent curling at the edges, this being common practice. The paper then passes under roller 31, on shaft 38 near the bottom of the machine, and thence rearwardly to the potash station and to the drier which may be any suitable or 'well' known construction and is not described herein.

Referring again to the application of moisture to the rear of the print before it reaches the conventional water Wash, I have found that if sitized side of the paper heated water vapor in small amounts. This vapor is applied in the vicinity of the roller or whatever device is employed for applying moisture to the back of the paper, the vapor preferably being applied simultaneously with the application of moisture to the back. This eliminates the necessity for a lengthy soaking period between the initial application of moisture and'the conventional water Wash applied to the front of the paper.

By applying water to the rear ofthe paper prior to washing the front as in the method disclosed herein, oxidation appears to be started with the chemicals that are deeply imbedded in the fibers of the paper prior to removing any chemical from the surface of the paper. This brings about a better blue print with deeper color from the same light exposure. This is probably due to the fact that if running water is first applied to the coated side of the sheet, the washing action or force of the water removes not only the outer layer of completely reduced insoluble chemical but also a certain portion of the incompletely reduced chemical buried in the fibers of the paper stock. This partially reduced chemical is capable of producing some of the insoluble blue substance which is Turnbulls blue, if it is allowed to oxidize. The running water, as explained, removes the partially reduced chemical before it has time to oxidize, whereas by applying the water to the back of the sheet, the chemical is moistened 'enough to start oxidation but with no tendency to remove it or mechanical action to remove it. This initial step as thus described may be termed a soaking process or step.

In hastening the oxidation process by the use of moisture laden air, it is not necessary to sup ply the vapor in the form of steam. The vapor may be supplied from any suitable source, either that arising from the warm water issuing from the pipe 25 or through a spray pipe 39, supplied for that purpose. With this double application of moisture to the front and rear of the paper, the moisture from the rear does not have to penetrate the entire thickness of the paper in order to oxidize the outer layer of the chemical. It is evident that either method may be used singly and that the combination of the two assures good results on high speed continuous blue printing machines.

In Fig. 2 the printing portion of the machine may be assumed to be the same as that'previously described. The span of paper l2, after leaving the tension roller II (the same as in Fig. 1)

. passes upwardly and over a water tank or trough top. The paper passes over spaced rollers 4|,

4| and a middle roller 42 which latter dips into said trough 40. As shown in dotted lines,- one of the rollers 4| is mounted on adjustable arms 43 to elevate the span of paper above the roll 42. The trough is keptfull of water from the reservoir 44. The roll 42 may be rotated in either direction, i. c. with or against the direction of travel of the paper, depending on whether more or less moisture is desired at the under surface of the same. From this initial moistening equipment the span of paper may pass directly to the usual water wash, or, in the case of paper traveling at a high rate of speed, a second application of water to the rear thereof may be desirable. In such cases a second trough 45 is provided with a roller 46 dipping therein and auxiliary rollers 41, 48, somewhat similar to those previously described, .The roller 48 may be mounted on 'an adjustable arm 49 to permit elevation of the span of paper above the roller 46 and thus avoid sticking when the machine stops.

Said water wash, indicated generally by reference 50, may be similar to that previously described inconnection with Fig. 1

In Fig. 3 another modification is shown in which the span of paper II, after leaving the A by passing under curved or bowed bars 56, in a manner well understood in the art. The water in this tank is not violently agitated but is comparatively still. The excess chemical which falls fromthe paper descends in the tank and is not carried along the surface in a way that would cause bleeding. Also, the initial application of water to the rear of the paper further insures against bleeding. From this tank the paper passes to the usual water wash, indicated generally by reference 51, which will be understood from the previous description of similar devices for washing the front of the print.

In Fig. '4 I have illustrated a modification of a different type, which might be said to involve a method of blotting the sensitized surface with moist, absorbent material after exposure, to withdraw the chemicals which it is desired to remove from the coated surface and to supply the necessary liquid. If this absorbent pad or blotter is pressed firmly against the surface of an exposed blue print for a few seconds, without sliding the pad along said surface, it will be found upon removal that the unexposed areas are white or practically free from the unreduced chemical and that on the exposed portion of the print not only the loose outer layer of ferrous compound has been removed but oxidation has started sufliciently to prevent bleeding or running of the color when the print is subsequently subjected to the regular treatment with running water or a water bath.

In this apparatus the band of blue print paper 12, after issuing from the printing section as heretofore, passes under a tension roller I1, thence upwardly over an idle roller 58 and down under rollers 59 and 60, upwardly and over roller 6| near the top of the frame of the attachment and thence downwardly around larger roller 62 which is mounted on a suitable shaft 63.

The material for accomplishing the blotting or absorbing action is,in this case, a moist endless belt 64 of suitable material such as felt, which belt passes around rollers 65, 66, mounted near the main roller 52, said belt passing downwardly around rollers 61 and 68, which latter are mounted in a container or tank 69. The roller 61 is mounted on a pivoted arm provided with a spring 1| which maintains suitable tension on the endless belt. The latter, it will be seen, is caused to bear against the coated side of the sheet of blue print paper l2 where it passes, around the roll 62 and is held in firm contact therewith, withoutslippage, for more than half of the circumference of the roller 62. The length of thepath of travel of the moist absorbent belt while it is in contact with the blue print, may be varied by adjusting the arm 12 on which the roller 66 is mounted, said arm being mounted to swing about the axis of the shaft 63. The span of paper has its coated side I2 uppermost as it leaves the printer andpasses under the tension roller 11, one of the purposes of the additionalrollers between said tension roller and the main roller 62 being to turn the paper upside down during'its travel so that its coated surface may be brought in contact with the absorbent belt as both spans pass around said main roller.

It is necessary to wash from the absorbent belt the chemicals which adhere thereto while it is in contact with the exposed surface of the blue print paper, and for this purpose said belt is passed through a water bath in the tank 69. The descending span is washed-with water by means of a spray issuing from the pipe 13, the water being applied to the side of the belt which was in contact with the blue print. This tends to wash the chemicals from the belt, which washing is further accomplished as the latter passes through the water bath in the tank, the level of the water being maintained by a suitable overflow pipe 14. If desired, a revolving brush or brushes such as may also be employed to aid in removing any surplus chemical from the belt. If the chemical were not removed it would, of course, be brought into contact with the surface of the print during the continued travel of the endless belt around the main roller and would stain the blue print, due to the chemical reaction which would take place.

After the blue print paper leaves the main roller 62, it passes through a conventional water wash, indicated at I6, but without any bleeding an endless belt of absorbent material beingpressed against said coated side, and caused to travel with the blue print paper. In the modified form of the device, the moist absorbent material forms an outer layer on a roller and the coated side of the paper passes over the roller facing inwardly instead of outwardly, and hence is in contact with the absorbent surface of the rollers Thus in both cases, the exposed surface is brought into direct contact with the blotting material, and travels therewith without slipping relatively thereto. In the drawings (Fig. I1 indicates the roller having a felt or other absorbent cover-.

ing 18 and mounted to dip in a suitable tank 19, the water level in which is controlled by an overflow pipe, as previously described. A spray of water from a pipe 80 is directed upwardly against the lower part of the roller to wash the chemical therefrom in addition to the washing that the roller receives in turning with its lower part submerged in the water bath.

The operation described in connection with the apparatus of Figs. 4 and 5 might be called a mechanical method of applying moisture to the surface of a blue print and removing the loose, exposed chemical as well as the underexposed chemical therefrom and without the possibility of any migration of the blues into the whites.

I claim:

1. The method of making non-bleeding photoprints comprising coating a sheet of water-permeable material with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, exposing portions of the coated surface to light, applying water to the rear surface only of said sheet to initiate oxidation without causing encroachment of the chemicals in the reduced areas upon those in the unreduced areas, applying a water wash to said sheet after. a time interval sufllcient to insure such oxidation and thereafter subjecting the same to a stronger oxidizing agent.

2. The method of making non-bleeding blueprints comprising coating a sheet of water-permeable material with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, exposing portions of the coated surface to light, applying a puddle of water to the upper surface only of said sheet when the .same is traveling substantially horizontally in inverted position, whereby the water soaks through said sheet and starts initial oxidation without causing running of the blue color into the white areas.

3. The method of making non-bleeding blueprints comprising coating a sheet of water-permeable material with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid. exposing portions of the coated surface to light, passing said sheet over a moistened roller with the coated side uppermost, whereby the moisture permeates said sheet and initiates oxidation without causing running of the blue color into the white are".

4. The method of making non-bleeding blueprints comprising coating a sheet of water-permeable mat'erial with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, exposing portions of the coated surface to light, pressing the uncoated side of said sheet against a surface moistened with water, whereby the moisture soaks through said sheet and reacts with the chemicals thereon without causing running of the blue color into the white areas.

5.The method of making non-bleeding blueprints comprising coating a sheet of material with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, exposing portions of the coated surface to light, pressing the coated side of said sheet against a sheet of absorbent material moistened with water, and separating the two without sliding one on the other, whereby the loose outer layer of chemicals is removed by said absorbent material without causing running of the blue color into the white areas.

6. The method as in claim 5 with the added steps of washing the said removed chemicals from said absorbent sheet and thereafter recontacting said absorbent sheet with said coated side, and repeating the cycle of operations indefinitely.

7. The method as in claim 5 in which the chemicals removed by said absorbent material are thereafter removed from said absorbent material to permit reuse of the latter.

8. The method of making non-bleeding blueprints comprising coating a sheet of material with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, exposing portions of the coated surface to light, pressing the coated side of said material against a moving layer of moistened absorbent material while said sheet is traveling I therewith, and thereafter separating said sheet and said layer, whereby oxidation of the exposed portions is begun during said contact and removal of the chemicals from the unexposed portions of said surface is effected.

9. The method as in claim 8, in which said removed chemicals are washed from said moving layer of absorbent material by passing the same through a bath, and thereafter again bringing said layer into contact with the coated side of said traveling sheet, in a continuous operation.

10. The method of making non-bleeding blueprints comprising coating a sheet of water-permeable material with a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, exposing portions of the coated surface to light, applying water to the rear surface only of said sheet and applying water vapor to the coated surface of said sheet, to initiate oxidation without causing encroachment of the chemicals in the reduced areas upon those in the unreduced areas, subsequently applying a water wash to said sheet and thereafter subjecting the same to a stronger oxidizing agent.

11. The method of developing an exposed lightsensitized layer comprising a ferricyanide of an alkali metal and a light sensitive ferric ammonium compound of an organic acid, in close and relatively immovable contact with an absorbent layer of material, which consists in applying water to said absorbent layer whereby the moisture held thereby is supplied to the dry sensitized layer substantially evenly in small quantities, sufiicient to start oxidation, but insuflicient to cause migration of the chemicals in the reduced areas into the unreduced areas.

12. The method of developing exposed blueprint paper, which comprises the step of moistening the paper, by capillary attraction of fibers near the exposed surface, by means 01' water in a moist capillary medium more remotetherei'rom.

13. The method of developing exposed blueprint paper, which comprises the step of moistening the chemical bearing portions of the exposed paper with an evenly distributed amount of water insufflcient to supersaturate the paper.

14. The method of making blueprints, comprising coating a sheet 01. material with a light sensitive compound, exposing portions of the coated surface to light, pressing the coated side of the dry sheet against a sheet of absorbent material moistened with a developer, separating said two 15. The method of making blueprints which comprises coating a sheet of material with a light sensitive compound rendered insoluble in water by exposure to light, exposing portions of the coated surface to light, contacting the coated side of the unmoistened material with a layer of moistened, absorbent material traveling in an endless circuit, said sheet moving with said traveling, absorbent material during part of said circuit without slipping thereover, separating said sheet and said layer, whereby development of the exposed portions is begun during said contact and removal of the chemicals from the unexposed portions of said surface is effected by said contact and separation, and removing said chemicals from said absorbent material, whereby the traveling, absorbent material may be used continuously.

'HAROLD J. BRUNK. 

